Journal of Civil Engineering Beyond Limits (CEBEL)

Mehmet Uğur YILMAZOĞLU

In the study where the effect of polypropylene (PP) fibers on the mechanical properties of low plasticity silt soils was investigated, unconfined compressive strength (UCS) tests were carried out by adding PP fiber additives to the soil at different rates (0%, 0.4%, 0.8%, 1.25%) and lengths (6 mm and 12 mm). The Taguchi method analyzed the experimental results using signal-to-noise (SN) ratios. The findings show that PP fiber additive significantly increases the strength and ductility behavior of the soil. It was determined that the unconfined compressive strength also increased with the increase in the fiber ratio. It was also determined that the fiber size was adequate on the strength. While 6 mm long fibers provided a more regular and stable strength increase, it was determined that the effect of 12 mm long fibers varied depending on the fiber ratio in the mixture. A significant 1.25% fiber ratio and 6 mm long fibers were determined to give optimum results. SN analysis results were evaluated according to the "bigger is better" principle, and the highest SN ratios were obtained at 1.25% fiber ratio. The study results show that PP fibers are an effective additive in improving low-plasticity silty soils and provide an economical solution. These results show the usability of PP fibers in soil engineering projects.

https://doi.org/10.36937/cebel.2024.1974

Saad Issa Sarsam

Asphalt concrete mixture exhibit Visco-elastic behaviour under vehicular loading. In the present work, two types of additives (silica fumes and coal fly ash) have been implemented to modify asphalt binder. Asphalt concrete mixtures were prepared and subjected to laboratory roller compaction in a slab Mold. Beam specimens were obtained from the slab samples and tested for fatigue resistance under dynamic flexural stresses at 20℃ environment using constant strain level of 750 microstrain. The variations in the failure mode from Visco-elastic to Visco-plastic was monitored. It was observed that during the Visco-elastic stage of failure, implication of additives exhibits higher flexural stiffness as compared with the control mixture. However, the flexural stiffness declined by (66.6, 99 and 97) % for (control, fly ash treated, and silica fumes treated) mixtures respectively at 20 seconds of practicing the dynamic flexural stresses. However, after the 20 seconds of loading, the Visco-plastic stage of failure starts, and the flexural stiffness declined dramatically by (91.6, 98.7, and 95.8) % for (control, fly ash treated, and silica fumes treated) mixtures respectively. The deformation during the Visco-elastic stage increased by (6.8 and 5) % for (fly ash and silica fumes) treated mixtures respectively as compared with the control mixture. Through the Visco-plastic stage of failure, it can be noticed that at failure, the cumulative dissipated energy increases by (1.72 and 1.4) folds and the phase angle increase by (1.5, 1.25) folds for mixtures treated with fly ash and silica fumes respectively as compared with the control mixture.

https://doi.org/10.36937/cebel.2024.1952

Baiti Akilu Boyi Dangoma Kabiru Umar Nurudeen Yusuf Mahmud Yakubu

Rice husk ash (RHA) is a promising pozzolanic alternative material for partial replacement of ordinary Portland cement to increase the durability and strength of concrete. This study examines the use of Rice Husk Ash (RHA) as a partial replacement for Ordinary Portland Cement (OPC) in the production of hollow cement blocks. The aim is to evaluate the impact of RHA on the compressive strength, workability, and water absorption properties of the blocks. RHA was introduced as a replacement for OPC at levels of 0%, 25%, and 50%, and tests were conducted after 7 and 14 days of curing. The results indicate that increasing RHA content leads to a reduction in compressive strength, with the 50% RHA mix exhibiting the lowest strength. This is attributed to the porous nature of RHA, which weakens the cementitious matrix. However, workability improved as RHA content increased, due to its water-reducing properties. The water absorption of the blocks also increased with higher RHA content, corresponding to the increased porosity. Despite the strength reduction, the pozzolanic activity of RHA suggests potential for long-term strength gains. The findings demonstrate that RHA can be a viable alternative for cement in non-structural applications, contributing to sustainable building practices by utilizing agricultural waste and reducing the reliance on cement. This research supports the integration of RHA into the construction industry as an eco-friendly material, promoting both waste management and carbon footprint reduction.

https://doi.org/10.36937/cebel.2024.1948

Wilson Uwemedimo Nyong Nuhu Abubakar Eneye Adeyemi Festus Oluwasogo Odeyemi Samson Odeyemi Nurudeen Yusuf

This research examines the properties and durability of green and hardened concrete incorporating selected agro-based pozzolans: rice husk ash, locust bean pod ash, sugarcane bagasse, soya bean pod ash, and maize cob ash. These pozzolans were calcined and analyzed using X-ray fluorescence (XRF) to replace cement in concrete cubes, which were cured over 7, 14, 21, and 28 days. The findings indicate that all pozzolans meet ASTM C618 requirements. Specifically, rice husk ash, sugarcane bagasse, and maize cob ash qualify as Class C pozzolana, while locust bean ash and soya bean ash are classified as Class F. The inclusion of these pozzolans increased the consistency, initial, and final setting times of cement. Consistencies ranged from 33% to 39.5%, with initial setting times from 74 to 225 minutes and final setting times from 152 to 400 minutes. The selected pozzolans slightly reduced the workability of the concrete but enhanced its durability, significantly improving resistance against aggressive media, including H2SO4, NaCl, and wastewater, at a 10% replacement level. This study highlights the potential of agro-based pozzolans as sustainable alternatives to conventional cement, offering environmental benefits and improving concrete performance in harsh conditions.

https://doi.org/10.36937/cebel.2024.1950

AYSAN ARDALANI ABDULKADİR CÜNEYT AYDIN

In evaluating the seismic performance of existing multi-story buildings, strain-based static pushover and time-history nonlinear analyses are traditionally used, as stated in the regulations. In addition, by evaluating the performance levels of symmetrical and asymmetrical structures, it will also be possible to design the mechanism with damping energy capacity that will completely absorb the earthquake energy in case of an inadequate situation in absorbing the earthquake energy. In this study, using real earthquake data, the usability of the energy-based performance analysis approach in the structure was investigated on a 20-story steel structure with rigid connections for symmetric and asymmetric structures. This study was conducted to demonstrate the usability of the energy-based method in evaluating the performance level of buildings under the effect of several earthquakes. In addition, the energy-based method was preferred to determine how much earthquake energy generated in the buildings could be distributed in symmetrical and asymmetrical structures. The selected 11 earthquake data were scaled and the input energies to the structure and the energies distributed by the structure (dissipated hysteretic energy, modal energy, dumping energy, and kinetic energy) were analyzed. Additionally, moment-rotation and axial force-strain behaviors were evaluated for the performance levels of the inspected symmetric and asymmetric structures. At the end of the study, the energy-based concept was confirmed by comparing it with the static pushover analysis results in determining the seismic performances of high-rise structures with very low dynamic mass participation rates. Energy-based analyses have shown that the symmetrical structure absorbs earthquake energies more than the asymmetrical structure and remains at the immediate occupancy (IO) level, as expected. It was concluded that the asymmetric structure remained at a controllable damage (LS) level. Energy-based evaluation has been used as a performance analysis method in the literature. In addition to performance analysis, this study aimed to calculate how much energy is required for the damping mechanism to be added to the structure so that an asymmetric structure behaves like a symmetric structure. This constitutes the original value of the article. So, it has been determined that in order for the asymmetric model to be at the immediate use level, a damper with an energy capacity of 0.062 m2/sec2 is needed, which can absorb earthquake energy from the outside, depending on the building mass.

https://doi.org/10.36937/cebel.2024.1976